Tie rod connection pivot assembly

ABSTRACT

A wheel end assembly comprising upper and lower arms and a tie rod coupled to a wheel carrier at an outer tie rod joint. A pin member is disposed between upper and lower mounting extensions of the wheel carrier or extends from a single mounting extension. The pin member comprises a first end, a second end and an expanded ball portion between the first and second end. The expanded ball portion is offset toward one of the first and second ends. The tie rod joint is defined by a pivotal coupling of the tie rod end to the pin member. A pivot point is defined between the tie rod end and the expanded ball portion, wherein the pivot point is closer to one of the first and second ends of the pin member to align the tie rod with the arms in a substantially parallel orientation to reduce bump steer.

CROSS REFERENCE TO RELATED APPLICATION[S]

This application claims priority to U.S. Provisional Patent Applicationentitled “TIE ROD CONNECTION PIVOT ASSEMBLY,” Ser. No. 62/537,651, filedJul. 27, 2017, the disclosure of which is hereby incorporated entirelyherein by reference.

BACKGROUND OF THE INVENTION 1. Technical Field

This invention relates generally to automotive equipment, and morespecifically, to an improved tie rod connection assembly for anautomobile.

2. Description of the Related Art

In the evolution of the modern automobile, the proper handlingcharacteristics of the vehicle have become increasingly more important.Automobile manufacturers attempt to design the suspension system toprovide predictable steering input, while at the same time recognizingthat production vehicles are used by a broad range of drivers. Alsoimportant to automobile manufacturers are cost, reliability and ease ofrepair. Thus, manufacturers of modern automobiles attempt to balancemany factors in designing suspension systems, which often results incompromises in certain areas.

In recent years, all-terrain vehicles (ATVs) have gained widespreadpopularity. ATVs are commonly used in hunting, trail riding and utilityapplications such as the wide variety of maintenance activities whichtake place on a farm. Attachments are available for ATVs for use inutility applications such as plowing snow, mowing grass and haulingmaterials.

Perhaps the most common ATV application is trail riding. Trail riding onan ATV allows an ATV enthusiast to travel through areas which are notaccessible by ordinary automobiles. Modern ATVs, can cover ground veryrapidly and can cover great distances. Frequently, ATV enthusiasts ridetheir ATV for many hours straight and cover many miles. If the rider issubjected to excessive jarring while traveling over rough terrain,operator fatigue may result particularly during a long ride. During suchlong rides, an ATV may be used to carry a rider through a wide varietyof terrain. Terrain which may be encountered includes forests, swamps,and deserts. Frequently ATVs are called upon to travel across ruggedterrain at relatively high speeds.

Part of the thrill of riding an ATV is encountering challenging terrain,and through the performance of the ATV and the skill of the riderpassing through the terrain. The ability to tackle challenging terrainmay depend on the performance of the steering systems, suspension, andthe interface between the rider and the ATV. These elements each affectthe riding experience enjoyed by the ATV enthusiast.

Off road vehicles in the form of ATV's (all-terrain vehicles) and UTV's(utility task vehicles) are produced by numerous manufacturers.Purchasers and users of these vehicles frequently desire to fit themwith larger tires to give them greater agility in traversing roughterrain. To fit larger tires on these vehicles, it is common to installa lift kit to raise the vehicle body to make room for the larger tiresand to increase ground clearance. Typically, a lift kit will adverselyaffect constant velocity (CV) joint angles and necessitate replacementof the original equipment axles, including CV joints. Even with theseupgrades, steering geometry can be compromised and bump steer, forexample, can be introduced. Still further, the final drive ratiomeasured as available force at the thread surface of the oversize tiresis reduced in proportion to the size increase. The foregoing reveals aneed for an aftermarket system to mount oversize wheels on off roadvehicles that avoids the disadvantage of ordinary lift kits.

The factory set-up for a conventional steering joint includes a largebump steer which contributes to the vehicle being unstable, hard todrive and with a large amount of rough feedback in the steering wheelwhen driving off road.

Thus, the need exists to provide a cost-effective system that reducesbump steer without dramatically altering the OE steering system.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a steering assembly with anoffset pivot point on the spindle to reduce bump steer, andspecifically, a pivotal coupling is provided between the tie rod end andthe wheel carrier pin member wherein an expanded ball portion of the pinmember is offset from center to align the tie rod and the upper andlower control arms to be substantially parallel.

Further, a method is provided of coupling a wheel end assembly to avehicle frame to improve bump steer of a vehicle, comprising the stepsof providing a vehicle frame and a wheel carrier coupled to said vehicleframe by a suspension, wherein the suspension includes at least oneupper arm and at least one lower arm. A tie rod is provided comprisingan elongated body member and a tie rod end. A pin member is coupled toat least one mounting extension on the wheel carrier, wherein the pinmember comprising a first end, a second end and an expanded ball portionbetween the first and second end. The expanded ball portion is offsettoward one of the first and second ends of the pin member tosubstantially align the tie rod with the upper and lower arm in asubstantially parallel position to thereby reduce bump steer. The tierod is coupled to the wheel carrier at an outer tie rod joint byinserting the pin member through the tie rod end, whereby the tie rodjoint is defined by a pivotal coupling between the tie rod end and theexpanded ball portion, such that a pivot point of the pivotal couplingis offset toward one of the first and second end of the pin member.

These and other features of the present invention will be apparent fromthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described by way ofexample with reference to the accompanying drawings. Although severalembodiments of the invention are described and shown in the followingdescription, like reference numbers identify like parts in each of thefigures, in which:

FIG. 1 is a perspective view of an ATV in accordance with the presentinvention.

FIG. 2 is a perspective view of an ATV in accordance with the presentinvention.

FIG. 3 is a perspective view of an assembly in accordance with anexemplary embodiment of the present invention.

FIG. 4 is a perspective view of an assembly in accordance with thepresent invention.

FIG. 5 illustrates a conventional tie rod connection assembly.

FIG. 6 is a side and top perspective view of the wheel end assemblyaccording to the preset invention.

FIG. 7 is an enlarged partial view of the tie rod connection of FIG. 6showing the tie rod end pating with the pin member affixed to the wheelcarrier.

FIG. 8 is a side view of the tie rod connection with dimensionsaccording to an embodiment of the present invention.

FIG. 9 is a partial side and tope perspective view of a wheel endassembly according to an alternate embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are numberedidentically. The drawings, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope of theinvention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements. All otherelements employ that which is known to those of skill in the field ofthe invention. Those skilled in the art will recognize that many of theexamples provided have suitable alternatives that can be utilized.

Bump steer or roll steer is the term for the tendency of the wheel of acar to steer itself as it moves through the suspension stroke. It istypically measured in degrees of steer per meter of upwards motion ordegrees per foot.

On modern cars the front suspension and steering links are designed sothat during a turning maneuver, body roll and suspension motions willnot influence the car to turn more sharply than the driver anticipates.On modern cars, the leading edge of the front tires move outwards as thesuspension is compressed, and inwards as the suspension droops(extends). This is known as “toe out” under bump and results in rollundersteer. During a turn, body roll will cause the outside suspension(relative to the curve) to compress and the inside suspension to droop(extend).

Bump steer causes a vehicle to turn itself when one wheel hits a bump orfalls down into a hole or rut. Excessive bump steer increases tire wearand makes the vehicle more difficult to handle on rough roads. Forexample, if the front left wheel rolls over a bump it will compress thesuspension on that corner and automatically rotate to the left (toeout), causing the car to turn itself left momentarily without any inputfrom the steering wheel. Another example is when most vehicles becomeairborne their front wheels will noticeably toe in. Typical values arefrom two to ten degrees per meter, for the front wheels.

The linearity of the bump steer curve is important and relies on therelationship of the control arms and tie rod pickup points, and thelength of each part. As the suspension goes through bump and droop, eachpart follows an arc resulting in a change of effective length. Whicheverparts are longest tend to have less change in effective length becausetheir arc radius is longer. This is the determining factor in designedbump steer. Another factor that affects bump steer is bushing complianceand deflection and arm bending. During a turn, if some or all of thebushings deflect then their pickup points have changed. If any of thearms and tie rods bend, then their effective length will changeresulting in a change of toe.

FIG. 1 is a perspective view of an ATV 100 in accordance with thepresent invention. ATV 100 includes two front wheels 102 and two rearwheels 104. A set of handle bars 106 are coupled to the front wheels 102for steering the ATV 100. An engine 108 is typically used to power therear wheels 104, and in some cases also the front wheels 102. ATV 100also includes a straddle-type seat 110 and foot rests for use by a riderof the ATV. In the embodiment of FIG. 1, engine 108 and seat 110 areboth preferably coupled to a frame 120 of the ATV 100. Each of the frontwheels 102 and rear wheels have a momentary ground contact point 122.The momentary ground contact points 122 of the wheels define a wheelcontact plane 124. In the embodiment of FIG. 1, each of the front wheels102 is coupled to frame 120 by a front suspension and each of the rearwheels 104 is coupled to frame 120 by a rear suspension.

FIG. 2 is a perspective view of an UTV 15 with wheels 12. This inventionis equally applicable to both ATVs and UTVs as will be described below.

FIG. 3 is a perspective view of an assembly 126 in accordance with anexemplary embodiment of the present invention. Assembly 126 includes aframe 120, and a suspension 128 comprising an upper arm 130, and a lowerarm 132. In the embodiment of FIG. 2, upper arm 130 is rotatably coupledto frame 120 at a first joint 138A and a second joint 140A. Also in theembodiment of FIG. 3, lower arm 132 is rotatably coupled to frame 120 ata first joint 138B and a second joint 140B.

Suspension 128 also includes a wheel carrier 134 that is coupled toupper arm 130 and lower arm 132. In the exemplary embodiment of FIG. 3,an outer end of upper arm 130 is coupled to an upper portion of wheelcarrier 134. Also in the exemplary embodiment of FIG. 2, an outer end oflower arm 132 is coupled to a lower portion of wheel carrier 134. A hub136 is preferably rotatably coupled to wheel carrier 134.

In the embodiment of FIG. 3, upper arm 130 and lower arm 132 are coupledto wheel carrier 134 by ball joints 180. Ball joints 180 preferablyprovide three rotational degrees of freedom. The rotational degrees offreedom provided by ball joints 180 allow suspension 128 to move betweena full compression position and a full extension provision and at thesame time allow wheel carrier 134 to rotate about a steering axis 182.

Assembly 126 also comprises a steering system that is configured torotate wheel carrier 134 about steering axis 182. Steering system 148includes a steering column 150 and a left tie rod 152A. An outer end ofleft tie rod 152A is pivotally coupled to a protrusion 154 of wheelcarrier 134. Steering column 150 is preferably rotatably supported byframe 120. A pair of handle bars or steering wheel (not shown) may befixed to steering column 150 proximate a distal end thereof.

Suspension 128 also includes a spring assembly 142 having a first endrotatably coupled to frame 120 and a second end rotatably coupled tolower arm 132. In the embodiment of FIG. 3, spring assembly 142 includesa shock absorber 144 and a spring 146 that is disposed about shockabsorber 144.

FIG. 4 is a perspective view of an assembly in accordance with thepresent invention. Assembly comprises a steering system 248 including asteering column 250. In FIG. 4 it may be appreciated that a steering arm256 is fixed to steering column 250 proximate a proximal end thereof. Insome applications, a pair of handle bars or a steering wheel may befixed to steering column 250 proximate a distal end thereof.

In the embodiment of FIG. 4, the proximal end of steering column 250 isrotatably supported by a mounting bracket 258. Mounting bracket 258 alsorotatably supports a left intermediate arm 260A and a right intermediatearm 260B. Left intermediate arm 260A is coupled to steering arm 256 by aleft link 262A, and right intermediate arm 260B is coupled to steeringarm 256 by a right link 262B.

Steering system 248 also includes a left tie rod 252A and a right tierod 252B. Left tie rod 252A includes an inner joint 264A and an outerjoint 266A. In FIG. 3 it may be appreciated that left tie rod 252A ispivotally coupled to a protrusion or extension 254 of a wheel carrier234 (i.e., single shear example of wheel carrier) at outer joint 266. InFIG. 3 it may also be appreciated that left tie rod 252A is pivotallycoupled to left intermediate arm 260A at inner joint 264A.

Right tie rod 252B includes an inner joint 264B and an outer joint 266B.In FIG. 4 it may be appreciated that right tie rod 252B is pivotallycoupled to right intermediate arm 260B at inner joint 264B. Right tierod 252B is preferably also coupled to a right wheel carrier (not shownin FIG. 4) at outer joint 266B. Inner joints 264A, 264B and outer joints266A, 266B preferably provide three rotational degrees of freedom. Inthe embodiment of FIG. 2, inner joints 264A, 264B and outer joints 266A,266B comprise ball joints.

FIG. 5 illustrates a conventional joint/ball joint on the steeringmechanism of a UTV. The tie rod 510 is pivotally connected at the tierod end 512 to the pin 520 mounted to the double-sheer type carrierhaving an upper extension 532 and lower extension 534 integrally formedas part of the wheel carrier 530. Rubber grommets 540 may be provided toprotect the joint from dirt, dust and debris. The conventional joint ison the end of the steering tie rod and is a connection point from thesteering rack and pinion to the outer spindle where the ball portion 525of the pin is disposed at the midpoint of the pin 520; e.g., thedistances “x” are equal. In other words, the ball portion 525 o the pin520 is disposed at a midpoint between the upper extension 532 and thelower extension 524 of the wheel carrier 530. In the conventional setup, there is a large amount of bump steer, which means that as thesuspension cycles up and down going over bumps, rocks, jumps, etc., thetoe setting changes dramatically. Typical alignments are 0.125-0.250″toe in; that is the front of the tires is closer to each other than therear of the tires so the car tracks straight. Typical changes in toesetting (bump steer) for an off road car are under an inch. Thisconventional arrangement has 4 inches of bump steer. This large bumpsteer contributes to the car being unstable, hard to drive and a lot ofrough feedback in the steering wheel when driving off road.

With reference to FIG. 6, the present invention will focus on thepivoting connection section where the tie rod is coupled to the wheelcarrier; e.g. where the left tie rod 252A is pivotally coupled to aprotrusion 254 of a wheel carrier 234 at outer joint 266 shown in FIG.4. As shown in FIG. 6, the tie rod 552 connects to the pin 554 at apoint that is substantially lower than the conventional arrangement ofFIG. 5 in an effort to place the tie rod as well as the support arms(shown as 130, 132 in FIG. 3) in a substantially parallel position;i.e., substantially parallel with each other. In the arrangement of FIG.6, the pin member 554 is formed with a neck portion 554 a that iselongated above the ball portion 554 b as shown in FIG. 7, and the pivotpoint has been lowered to a point where the terminal end of the tie rod552 will actually contact the lower extension 564 when the tie rod 552is pivoted to its maximum angle of travel.

However, the arrangement shown in FIG. 6 is only one preferredarrangement envisioned by the present invention and confirmed throughactual use in the field. For example, the ball portion 554 b may beraised to be offset in the vertical direction to be closer to the upperextension 562 in some wheel end designs to make the tie rod moreparallel with the upper and lower support arms (see control arms 130,132 in FIG. 3). Alternatively, the inner connection point of the tie rodmay be likewise adjusted to align the tie rod with the upper and lowercontrol or support arms in a parallel arrangement.

Thus, according to the preferred embodiment of the invention, it isenvisioned that the upper arm, the lower arm and the tie rod should bepositioned as close to parallel as possible. This arrangement keeps allthree moving parts traveling on the same radius or arc as they travel upand down over bumps. If these suspension components are on differentarcs, then bump steer is created. On the one system (e.g., an X3system), it was discovered that the tie rod arc was higher than theupper and lower arms. By lowering the pivot point in the manner shown inFIG. 6, it was discovered that as the tie rod was moved closer toparallel the bump steer issue was reduced or eliminated. According tothe invention, specific tests are run to calculate the optimal pivotpoint for the tie rod and the outer joint to fix bump steer as much aspossible.

FIGS. 6 and 7 illustrate a double-shear wheel carrier 560 (i.e., havingupper and lower mounting extensions 562, 564) where the ball portion 554b of the pin 554 is lowered toward the lower mounting extension 564 ofthe double-shear wheel carrier 560.

As shown in FIGS. 6 and 7, the bump steer is reduced dramatically bylowering the pivot point on the spindle by an amount shown by thedifference between FIG. 5 and FIGS. 6 and 7. This change in pivot pointor lowering of the ball portion 554 b in this example gets the front endgeometry from a poor 4 inches of bump steer to under half an inch. Thetie rod/joint connection of FIGS. 6 and 7 provides a steering assemblythat is more drivable and allows the vehicle to drive straight when theoperator wants. The arrangement of FIGS. 6 and 7 has no negativefeedback in the steering wheel and the limited stress, and thearrangement saves front end parts as well.

FIG. 8 illustrates a side view of the tie rod connection with dimensionsadded to show the structural relationship of the different tie rodcomponents including the tie rod 552 and the pin member 554 with theneck portion 554 a and ball portion 554 b. The pivot axis “p” has beenmoved to below the midpoint of the pin member 554 as shown in FIG. 8.

With reference to FIG. 9, an alternate embodiment of the presentinvention where the wheel carrier 660 is designed with a single mountingextension or single shear 662. Again, the invention will focus on thepivoting connection section where the tie rod 650 is coupled to thewheel carrier 660 via a pin member 630; e.g. where the tie rod 650 ispivotally coupled to a single mounting extension 662 of a wheel carrier660 (e.g., at outer joint 266 shown in FIG. 4). As shown in FIG. 9, thetie rod end 652 of the tie rod 650 connects to the ball portion 634 ofthe pin 630 at a point that is offset from the mounting extension 662 ofthe wheel carrier 660 as compared to the conventional arrangement ofFIG. 5. Indeed, the pin member 630 is formed with a neck portion 632that is elongated below the ball portion 634 as shown in FIG. 9 in sucha manner that the tie rod end 652 is raised above the mounting extension662 because, for this specific wheel end assembly, the bump steer isimproved by raising the intersection point between the tie rod end 652and the ball portion 634 of the pin member 554 to thereby place the tierod 650 in a parallel arrangement with respect to the control arms. Inthe design of FIG. 9, the pin member 630 is modified to move the ballportion 634 away from the extension 662; i.e., offset from the midpointof the in members 630.

While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and, therefore, the aim in the appended claims isto cover all such changes and modifications as fall within the spiritand scope of the invention and the following claims.

By way of example, included throughout this specification are thedimensions of the various components of a preferred embodiment of theinvention. The invention is not to be limited to the dimensions andspecific configuration of the individual components, but rather, otherdimensions and configurations that allow a suspension to be modified toimprove bump steer by raising or lowering the pivot point at the tie rodconnection outer end are envisioned by this invention.

The invention claimed is:
 1. A wheel end assembly comprising: a vehicleframe; a wheel carrier coupled to said vehicle frame by a suspension,said wheel carrier comprising at least a first and second mountingextension; an upper arm and a lower arm pivotally coupling said vehicleframe to said wheel carrier; a tie rod coupled to said wheel carrier atan outer tie rod joint; a pin member affixed to said first and secondmounting extensions of said wheel carrier and pivotally coupled to saidtie rod at said outer tie rod joint, said pin member comprising a firstend, a second end and an expanded ball portion between said first andsecond ends; said tie rod joint defined by a pivotal coupling of saidtie rod end with said pin member, wherein said expanded ball portion isoffset from center toward one of said first and second mountingextensions.
 2. The wheel end assembly according to claim 1, wherein saidexpanded ball portion is offset toward one of said first and second endsto align said tie rod to be substantially parallel with said upper andlower arms.
 3. The wheel end assembly according to claim 2, wherein saidwheel carrier comprises an upper mounting extension and a lower mountingextension, and wherein said expanded ball portion is positioned adjacentsaid lower mounting extension and distal from said upper mountingextension.
 4. The wheel end assembly according to claim 2, furthercomprising a flared portion between said expanded ball portion and saidfirst end.
 5. The wheel end assembly according to claim 2, furthercomprising a pivot point between said tie rod end and said expanded ballportion, wherein said pivot point is closer to said second end than saidfirst end.
 6. The wheel end assembly according to claim 5, wherein saidpivot point is less than 0.75 mm from said lower mounting extension. 7.The wheel end assembly according to claim 5, wherein said pivot point ismore than 2 mm from said upper mounting extension.
 8. The wheel endassembly according to claim 1, further comprising: a rubber grommetprovided on said pin member on opposite sides of said tie rod end.
 9. Awheel end assembly comprising: a tie rod adapted to be coupled to awheel carrier at an outer tie rod joint, said tie rod comprising anelongate body and a tie rod end; a pin member adapted to be disposedbetween upper and lower mounting extensions of said wheel carrier, saidpin member comprising a first end, a second end and an expanded ballportion between said first and second end, wherein said expanded ballportion is offset toward said lower mounting extension; said tie rodjoint defined by a pivotal coupling of said tie rod end, said pin memberpassing through an aperture in said tie rod end; and a pivot pointbetween said tie rod end and said expanded ball portion, wherein saidpivot point is closer to said lower mounting extension than said uppermounting extension.
 10. The wheel end assembly according to claim 9,further comprising: a flared portion between said expanded ball portionand said first end.
 11. The wheel end assembly according to claim 9,wherein said pivot point is less than 0.75 mm from said lower mountingextension.
 12. The wheel end assembly according to claim 9, wherein saidpivot point is more than 2 mm from said upper mounting extension. 13.The wheel end assembly according to claim 9, further comprising: arubber grommet provided on said pin member on opposite sides of said tierod end.
 14. A method of coupling a wheel end assembly to a vehicleframe to improve bump steer of a vehicle, comprising the steps of:providing a vehicle frame and a wheel carrier coupled to said vehicleframe by a suspension, said suspension including at least one upper armand at least one lower arm; providing a tie rod comprising an elongatedbody member and a tie rod end; providing a pin member coupled to atleast a first and second mounting extension on said wheel carrier, saidpin member comprising a first end, a second end and an expanded ballportion between said first and second end, offsetting said expanded ballportion toward one of said first and second mounting extensions tosubstantially align said tie rod with said upper and lower arm in asubstantially parallel position to thereby reduce bump steer; couplingsaid tie rod to the wheel carrier at an outer tie rod joint by insertingsaid pin member through said tie rod end, said tie rod joint defined bya pivotal coupling between said tie rod end and said expanded ballportion, wherein a pivot point of said pivotal coupling is offset towardone of said first and second mounting extensions.
 15. The methodaccording to claim 14, wherein said pivot point is less than 0.75 mmfrom said lower mounting extension.
 16. The method according to claim14, wherein said pivot point is more than 2 mm from said upper mountingextension.
 17. The method according to claim 14, further comprising:providing a rubber grommet around said pin member adjacent said tie rodend.